import sys
import re
from typing import Tuple

issue_patterns = [
    r"https://github.com/ydb-platform/[a-z\-]+/issues/\d+",
    r"https://st.yandex-team.ru/[a-zA-Z]+-\d+",
    r"#\d+",
    r"[a-zA-Z]+-\d+"
]

pull_request_template = """
### Changelog entry <!-- a user-readable short description of the changes that goes to CHANGELOG.md and Release Notes -->

...

### Changelog category <!-- remove all except one -->

* New feature
* Experimental feature
* Improvement
* Performance improvement
* User Interface
* Bugfix 
* Backward incompatible change
* Documentation (changelog entry is not required)
* Not for changelog (changelog entry is not required)
"""

def validate_pr_description(description, is_not_for_cl_valid=True) -> bool:
    try:
        result, _  = check_pr_description(description, is_not_for_cl_valid)
        return result
    except Exception as e:
        print(f"::error::Error during validation: {e}")
        return False

def check_pr_description(description, is_not_for_cl_valid=True) -> Tuple[bool, str]:
    if not description.strip():
        txt = "PR description is empty. Please fill it out."
        print(f"::warning::{txt}")
        return False, txt

    if "### Changelog category" not in description and "### Changelog entry" not in description:
        return is_not_for_cl_valid, "Changelog category and entry sections are not found."

    if pull_request_template.strip() in description.strip():
            return is_not_for_cl_valid, "Pull request template as is."

    # Extract changelog category section
    category_section = re.search(r"### Changelog category.*?\n(.*?)(\n###|$)", description, re.DOTALL)
    if not category_section:
        txt = "Changelog category section not found."
        print(f"::warning::{txt}")
        return False, txt

    categories = [line.strip('* ').strip() for line in category_section.group(1).splitlines() if line.strip()]

    if len(categories) != 1:
        txt = "Only one category can be selected at a time."
        print(f"::warning::{txt}")
        return False, txt

    category = categories[0]
    for_cl_categories = [
        "New feature",
        "Experimental feature",
        "User Interface",
        "Improvement", 
        "Performance improvement",
        "Bugfix",
        "Backward incompatible change"
    ]

    not_for_cl_categories = [
        "Documentation (changelog entry is not required)",
        "Not for changelog (changelog entry is not required)"
    ]
    
    valid_categories = for_cl_categories + not_for_cl_categories

    if not any(cat.startswith(category) for cat in valid_categories):
        txt = f"Invalid Changelog category: {category}"
        print(f"::warning::{txt}")
        return False, txt

    if not is_not_for_cl_valid and any(cat.startswith(category) for cat in not_for_cl_categories):
        txt = f"Category is not for changelog: {category}"
        print(f"::notice::{txt}")
        return False, txt

    if not any(cat.startswith(category) for cat in not_for_cl_categories):
        entry_section = re.search(r"### Changelog entry.*?\n(.*?)(\n###|$)", description, re.DOTALL)
        if not entry_section or len(entry_section.group(1).strip()) < 20:
            txt = "The changelog entry is less than 20 characters or missing."
            print(f"::warning::{txt}")
            return False, txt

        if category == "Bugfix":
            def check_issue_pattern(issue_pattern):
                return re.search(issue_pattern, description)

            if not any(check_issue_pattern(issue_pattern) for issue_pattern in issue_patterns):
                txt = "Bugfix requires a linked issue in the changelog entry"
                print(f"::warning::{txt}")
                return False, txt

    print("PR description is valid.")
    return True, "PR description is valid."

def validate_pr_description_from_file(file_path) -> Tuple[bool, str]:
    try:
        with open(file_path, 'r') as file:
            description = file.read()
        return check_pr_description(description)
    except Exception as e:
        txt = f"Failed to validate PR description: {e}"
        print(f"::error::{txt}")
        return False, txt

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: validate_pr_description.py <path_to_pr_description_file>")
        sys.exit(1)
    
    file_path = sys.argv[1]
    is_valid, txt = validate_pr_description_from_file(file_path)
    from post_status_to_github import post
    post(is_valid, txt)
    if not is_valid:
        sys.exit(1)